Process for treatment of gossypol in solvent-extracted cottonseed meal



March 10, 1953 M. BONOTTO 2,631,099

PROCESS FOR TREATMENT OF GOSSYPOL'. IN SOLVENT-EXTRACTED COTTONSEED MEAL Original Filed Nov. 26, 1948 W I AND EXCESS OF E REAGENT.

MEAL ou-r- 214? 1 c 0.052 GOSSYPOL 19 10 3 EJSTEHM ZONE 2 STEHM ZONE 17 i 102 SOLVENT EXTRHCTED 4 MEHL 1 -15 STEAM ZONE l iafg'f 12 INVENTOR. SULPH MICHELE Bo/vorro Patented Mar. 10, 1953 PROCESS FOR TREATMENT OF GOSSYPOL IN SOLVENT-EXTRACTED COTTONSEED MEAL Michele Bonotto, Princeton, N. J.

Original application November 26, 1948, Serial No. 62,132. Divided and this application May 15, 1951, Serial No. 224,760

7 Claims.

This invention relates to improvements in process and apparatus for treatment of gossypol in solvent-extracted cottonseed meal and comprises a division of my co-pending application Serial No. 62,132, filed November 26, 1948.

It is well known in the cottonseed crushing industry that the toxic substance called gossypol contained in the cottonseed must be destroyed or altered or made innocuous in order to have the pressed or extracted meal suitable for feeding animals. When presses are used to remove the oil from cottonseed, the problem of dealing with gossypol is simplified because the gossypol is altered or destroyed or made innocuous during the pre-cooking of the crushed seeds prior to pressing. This cooking process conventionally is done in order to rupture the oil cells contained in the seeds to make them ready for pressing and to facilitate the free-flowing of the oil during the pressing operation. At the same time, as stated above, the greater portion of gossypol is destroyed or altered or made innocuous during this cooking process, thus making the residual meal suitable for animal consumption.

The gossypol is apparently affected not merely by the heat treatment employed in the cooking. An important factor seems to be the presence of moisture, controlled during the cooking process to around 16% to 18%. The duration of the socalled cooking also has an important function, as also has the presence of live steam in the mass. In the cottonseed crushing practice, the treatment or cooking of the crushed or flaked seed prior to pressing is carried on in specially designed stack cookers under the following average conditions: temperature, 230 to 250 F.; duration from 70 to 90 minutes; initial moisture, from 16% to 18 which moisture is gradually reduced until at the end of the cooking operation the moisture content of the material is between 8% to When solvent is used instead of presses to extract the oil from cottonseed, the pre-cooking of the flaked or crushed seeds according to the above procedure has been found impractical because of the excessive amount of fine particles caused by the agitating devices of the cooker. Such fines impair the free-flowing of solvent throughout the mass of flaked seed in the extractor. In addition, such fines cause further complications because they are carried over with the miscells, at the exit of the extraction apparatus to the solvent recovery system.

Attempts have been made to destroy or render gossypol innocuous by cooking the meal, in accordance with previously-described procedure, after it has been solvent extracted. Such solventextracted meal usually contains from 1 to 2 of oil. However, the treatment of the gossypol by cooking after solvent extraction has, up to the present time, not been satisfactory because tests have shown that the initial gossypol content of solvent-extracted meal, which is around 0.9% on an 8% moisture basis, has only been reduced to 0.2%, and a meal in which the gossypol is so reduced is still not safe for feeding purposes.

Some success in reducing the gossypol content has been achieved in treating solvent-extracted meal in autoclaves at varyin pressures but again the results have not been found satisfactory; neither from the point of view of the percent of gossypol left intact in the meal nor from the practical point of view with respect to processing on a large scale, especially in solvent plants operating on the continuous principle.

Objects of my invention are to reduce the percentage of gossypol in the solvent-extracted meal to an amount that is considered safe for animal food, as for example, less than 0.05%; to utilize for this purpose a chemical reagent of a type in which the excess may, during the process of reducing the gossypol content to a safe proportion, be readily eliminated or steamed out so as to avoid the necessity of using additional chemicals to neutralize such excess, which additional neutralizing chemicals always leave in the product chemical compounds resulting from such neutralization, and thus to produce a final product that is free from such chemical compounds as well as from such excess of the reagent; to provide a reagent and a process of applying the same by the use of which the said reagent may be thoroughly distributed throughout the mass of meal being treated; to utilize a process and to employ apparatus in and by which the above result may be accomplished in a commercial plant operating on the continuous-operation principle; to reduce the time of treatment over prior art treatments, and to reduce the average of the temperature of such treatments while in no way deleteriously affecting the food value or other feeding factors of the meal.

Another object of my invention is to utilize the reagent in gaseous form and to inject such gas in proper'amount into the meal during a conveying movement thereof.

With these and other objects in view the invention comprises the combination of steps and members so combined as to coact and cooperate with each other in the performance of the functions and the accomplishment of the result herein contemplated, and the apparatus comprises in one of its adaptations the species or preferred form illustrated in the accompanying drawing in which:

Fig. 1 is an illustrative sectional view of apparatus similar to that shown in my Patent No. 2,277,361 except for the introduction of a gaseous reagent.

In accordance with my invention, I have discovered that by a cooking or steaming operation is connectedwith the conduit l3.

of the solvent-extracted meal in the presence of sulphur dioxide, I am enabled not only to reduce the percentage of gossypol in the meal to less than 0.05% (which amount is considered safe for animal consumption), but also to substantially reduce the time of the treatment, and to reduce the average temperature of the treatment, while in no way deleteriously affecting the food value of the meal.

My invention may be carried out in any conventional cooking apparatus known in the oilseed crushing industry, but I have obtained the best results by applying my invention in appa ratus similar to my continuous solvent eliminator (also called dryer) described in my said Patent No. 2,277,361 and by applying a process similar to that described in my Patent No. 2,191,255. My invention may also be carried on in apparatus similar to my patented apparatus, Patent No. 2,254,867, and in other forms of apparatus similar to apparatus on which I have patent applications now pending.

The advantages of using gaseous sulphur dioxide (S02) are, first, that the excess of the reagent is readily eliminated or steamed out dur- 'ing the-processand, second, there is no necessity touse chemicals to neutralize such excess, so that the final product is "free from chemical compounds resulting from such neutralization.

I have found that whenprocessing solvent extracted cottonseed meal in apparatus similar to the apparatus of my Patent No. 2,277,361 mentioned above, the time of treatment is reduced from the conventional 70 to 90 minutes to about '30 to 40 minutes. In addition, the temperature of the treatmentis reduced-from the conventional 240 F. to 216-F. or lower, and the gossypol content from'about 0.9% is reduced to about 0.05% or less (on an 8% moisture basis) The steaming process, according to the preferred form of my invention, was in tests effected in the following way. See Patent No. 2,277,361 for a'detailed description of the apparatus used in my tests. The solvent extracted meal containing approximately 1.03% oil, 8% moisture, :and 45% protein, was continuously introduced into the bottom -of;the apparatus at a rate of 5-lbs,per minute at room temperature of 64 F.

, -In the accompanying illustrative drawin I have shown a vertically-disposed 0r upright tank 1-0 having between its ends a plurality, and as shown three, steam treating sections l0 --I0 -|0, which is adapted to contain and 'be filled withsolidextracted material and into portion thereof with a cylindrical section H also adapted to contain a body of material of sufficient lengthand'density'to prevent downward blowing therethrough of steam admitted to the treating lsecti'ons hereinabove referred to. Adjacent to the bottom of the tank a feed opening [2 is provided through which'process'material isfed from a conduit l3'cont'aining a conveyor feed screw '14, and, as shown, a feed hopper 5 for extracted meal A conveyor screw I6 is mounted in the tank 10 and is adapted to convey upwardly through the cylindrical section ll all solid materials fed at the bottom through the opening 12. Such solid material at the end-of the conveyor screw 16 is forced still further upwardly successively into the varying steaming zones Ill -t0 and 10 respectively,

which are preferably free or continuous conveying mechanism. Thus, the section H3 communicates with the section 10 and is preferably sepa-- rated therefrom by a screw flight l1, while the section I00 is separated from the section Ill by screw flight l8, and a screw flight I9 is prefer ably provided in the zone l0. The solvent extracted meal may be fed through the hopper l5 and, in the preferred form of my invention, the reagent may be fed into the lower section of the tank I0 in gaseous form from a tank of gaseous sulphur "dioxide 20.

It "will be apparent that the apparatus shown in 'the accompanying drawing is similar in all respects to the apparatus shown and described in my said Patent #2,277,361 except for the means used for addition to the solvent extracted meal of sulphur dioxide whichfmay be added after or during the passing of the material into and through the hopper i5, and preferably the agent or its equivalent isinj'ect'ed in gaseous form into the lower portion H "of the tank I0 by the gas tank 20.

In said apparatus, three steaming zones are provided by blowing steam through three sets of jets, each set connected with a manifold. 'The duration of travel 'of the material, through the apparatus of the size "used in my tests, at the above rate was about 38 minutes. *Dry'saturated steam at 'lbs. pressure was expanded to a'tmospheric pressure and introduced in the bottom manifold of'the apparatus in *suchquantity so as to add moisture in the meal'equal to about 15% to 18%.

When the mixture of meala'ndsulphur dioxide, which travels continuously upward, reaches the lower steaming 'zone of theapparatuathesulphur dioxide gas passes through the column of upwardly moving material under treatment, driven by the live steam which i'sgoingtowards the uppe'r exit of the apparatus. Thecolumn of material traveling, as stated before, upward in an atmosphere of steam andthe sulphur'dioxide'gas passes through the second steaming zone which is located above the first-and is created by injecting superheated steam at a temperature of about 290 F. Then it reaches athird steamingzone created by injecting steam or the same duality as inthe'zone immediately below throllghthe maiilfold.

A sample of the meal so treated, taken after about 30 minutes of the treatment, showed a gossypol content of 0i054% "and a sample "taken at the exit of the apparatus after about 45 minutes or the treatment showed *a gossy'p'ol content of 0.052%. The temperature of th'e 'meal at the exit was 214 F.

"A maximum percentof gossypol in the meal,

on an 8% moisture basis,'of from 0.05% to 0L06'% is considered notobectionable for feetling purposes. Y Iffurth'er reduction of the gossypolis-"desired, an increase in the proportion "of the reagent to the meal undertre'atment and/or a longerpe'ribd of treatment may be used.

It isfalsojobvious that my lhventionmay be used with other forms 'ofc'ooking apparatiis or dryers without "departing from 'my invention.

Under the above conditions sulphur 'dioiiide ($02) 'in gaseous form was injected into the bottom ofa'drye'rsuch as hereinabove'des'cribed at the inlet of themeal in proportions 'by weight Of from 0.000055% to 0,0002% '01 the'h'ieal'linder process, accordin'gt'o the qualityofth'eoriginal basis and when 0.0000'7% proportion was used, the gossypol content was reduced to 0.053% on an 8% moisture basis.

The employment of the steaming zone H1, in which the steam is condensed for the purpose of increasing the moisture content of the meal to the desired percentage, is preferred though not absolutely essential because water may be added to the meal before entering the apparatus and the moistened meal may be preheated to approximately 210 F. so as to avoid further condensation of steam during treatment of the meal in the superheated steam zones. My preferred procedure is, however, more economical because the necessary moisture is added during the operation of heating the meal in the said lower zone [0.

Having described my invention, I claim:

1. A process for treatment of solvent-extracted cottonseed meal to reduce the gossypol content thereof to safe feeding proportions consisting in adding to the solvent-extracted meal sulphur dioxide in a proportion capable with moisture and heat of reducing the proportion of gossypol, and also subjecting the meal to moisture and heat during a conveying movement of the meal.

2. A process for treatment of solvent-extracted cottonseed meal to reduce the gossypol content thereof consisting in subjecting said solventextracted cottonseed meal to treatment with sulphur dioxide in a proportion capable with moisture and heat of reducing the proportion of gossypol, introducing into the solvent-extracted cottonseed meal moisture equal to approximately 18% of the meal, continuously moving a column of such solvent-extracted cottonseed meal in a substantially upward direction through a tank, then subjecting said moisture-containing meal in said tank to superheated steam injected into said column of material through said tank at a temperature between 260 and 350 F. and for a time period between thirty and sixty minutes, and thereafter discharging said treated meal and steam vapor from the said tank at a still higher level.

3. A process for treatment of solvent-extracted cottonseed meal to reduce the gossypol content thereof consisting in continuously moving a column of solvent-extracted cottonseed meal in a substantially upward direction through a tank, subjecting said solvent-extracted cottonseed meal to treatment with sulphur dioxide in a proportion capable with moisture and heat of reducing the proportion of gossypol, introducing into said column of meal through a lower portion of the tank steam expanded to atmospheric pressure in such quantity as to produce moisture in hot condition equal to approximately 18% of the meal, then subjecting said moisture-containing meal in said tank to superheated steam injected into said column of material through said tank at a level higher than that at which the moisture is introduced at a temperature between 260 F. and 350 F. and for a time period between thirty and sixty minutes, and thereafter dischargin said treated meal and steam vapor from the said tank at a still higher level.

4. A process for treatment of solvent-extracted cottonseed meal to reduce the gossypol content thereof consisting in continuously moving a column of solvent-extracted cottonseed meal in a substantially upward direction through a tank, subjecting said solvent-extracted cottonseed meal to treatment with sulphur dioxide in a proportion capable with moisture and heat of reducing the proportion of gossypol, introducing into the meal at the bottom portion of the tank steam expanded to atmospheric pressure in such quantity as to produce moisture in hot condition equal to approximately 18% of the meal, then subjecting said moisture-containing meal in said tank to superheated steam injected into said column of material through said tank at a level higher than that at which the moisture is introduced at a temperature between 260 F. and 350 F., and then at a still higher level further subjecting said column of meal to superheated steam by injecting the same at substantially the same temperature as in the zone immediately below, and thereafter discharging said material and steam from said tank at a still higher level.

5. A process for treatment of solvent-extracted cottonseed meal to reduce the gossypol content thereof consisting in introducing into the meal moisture to approximately 18% of the meal, continuously moving a column of such solvent-extracted cottonseed meal in a substantially upward direction through a tank, injecting through the lower portion of the tank into said moistened column of meal a vaporous chemical agent comprising sulphur dioxide gas equivalent to from 0.00005% to 0.0002% of the meal under process, then subjecting said moisture-containing meal in said tank to superheated steam injected into said column of material through said tank at a level higher than that at which the moisture is introduced at a temperature between 260 F. and 350 F. and for a time period between thirty and sixty minutes, and discharging said meal at a still higher level and also conjointly discharging the excess of said vaporous chemical agent and steam at a still higher level.

6. A process for treatment of solvent-extracted cottonseed meal to reduce the gossypol content thereof consisting in introducing into the meal moisture equal to approximately 18% of the meal, continuously moving a column of such solvenextracted cottonseed meal in a substantially upward direction through a tank, injecting through the bottom portion of the tank into said moistened column of meal sulphur dioxide gas, then subjecting said moisture-containing meal in said tank to superheated steam injected at a temperature between 260 F. and 350 '13. into said column of material through said tank at a level higher than that at which the sulphur dioxide gas is introduced and for a time period between thirty and sixty minutes, and discharging said meal at a still higher level and also conjointly discharging any excess of said sulphur dioxide gas and steam at a still higher level.

'7. A process for treatment of solvent-extracted cotton-seed meal to reduce the gossypol content thereof to safe feeding proportions consisting in subjecting the solvent-extracted meal to treatment with sulphur dioxide gas in a proportion capable with moisture and heat of reducing the proportion of gossypol, and also subjecting the meal to moisture and heat.

MICHELE BONOTTO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,884,779 Maybee Oct. 25, 1932 2,064,158 Harrell et al. Dec. 15, 1936 

1. A PROCESS FOR TREATMENT OF SOLVENT-EXTRACTED COTONSED MEAL TO REDUCT THE GOSSYPOL CONTENT THEREOF TO SAFE FEEDING PROPORTIONS CONSISTING IN ADDING TO THE SOLVENT-EXTRACTED MEAL SULPHUR DIOXIDE IN A PORPORTION CAPABLE WITH MOISTURE AND HEAT OF REDUCING THE PROPORTION OF GOSSYPOL, 